{ "node": { "id": "term:specific-heat-capacity", "type": "Term", "label": "Specific heat capacity", "properties": { "id": "specific-heat-capacity", "name": "Specific heat capacity", "abbr": "cₚ", "aka": [ "heat capacity", "specific heat" ], "section": "topic-thermal", "definition": "The heat needed to raise one kilogram of a material by one kelvin; multiplied by mass it gives a body’s heat capacity in J/K. Lithium-ion cells sit near 1,000 J/(kg·K), so a 0.5 kg pouch cell absorbs about 500 J per degree — the figure a thermal model uses to turn heat into temperature rise.", "formula": "Q = m·cₚ·ΔT", "unit": "J/(kg·K)", "related": [ "thermal-mass", "thermal-characterisation", "thermal-model", "heat-generation", "thermal-diffusivity" ], "example": { "title": "Estimate a temperature rise", "text": "A 0.5 kg body with cₚ = 900 J/(kg·K) requires 4500 J for a 10 K temperature rise if heat loss and phase change are neglected. The heat capacity of the whole body is 450 J/K." }, "url": "https://lemonergy.com/learn/glossary/specific-heat-capacity/", "mentions": [ "pouch-cell" ] } }, "edges": [ { "id": "edge:usesBlock/term:specific-heat-capacity/block:phase-change-mass", "source": "term:specific-heat-capacity", "target": "block:phase-change-mass", "type": "usesBlock", "properties": { "sourceFile": "studio-help-catalog.json", "scope": "Declared interface quantity or semantic operation; not a numerical validation claim" } }, { "id": "edge:usesBlock/term:specific-heat-capacity/block:thermal-mass", "source": "term:specific-heat-capacity", "target": "block:thermal-mass", "type": "usesBlock", "properties": { "sourceFile": "studio-help-catalog.json", "scope": "Declared interface quantity or semantic operation; not a numerical validation claim" } }, { "id": "edge:belongsTo/term:specific-heat-capacity/topic:topic-thermal", "source": "term:specific-heat-capacity", "target": "topic:topic-thermal", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:relatedTo/term:specific-heat-capacity/term:thermal-mass", "source": "term:specific-heat-capacity", "target": "term:thermal-mass", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:relatedTo/term:specific-heat-capacity/term:thermal-characterisation", "source": "term:specific-heat-capacity", "target": "term:thermal-characterisation", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:relatedTo/term:specific-heat-capacity/term:thermal-model", "source": "term:specific-heat-capacity", "target": "term:thermal-model", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:relatedTo/term:specific-heat-capacity/term:heat-generation", "source": "term:specific-heat-capacity", "target": "term:heat-generation", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:relatedTo/term:specific-heat-capacity/term:thermal-diffusivity", "source": "term:specific-heat-capacity", "target": "term:thermal-diffusivity", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/specific-heat-capacity/pouch-cell", "source": "term:specific-heat-capacity", "target": "term:pouch-cell", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:illustratedBy/term:specific-heat-capacity/visual:thermal", "source": "term:specific-heat-capacity", "target": "visual:thermal", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } } ], "neighbors": [ { "id": "block:phase-change-mass", "type": "Block", "label": "Phase-change thermal mass", "properties": { "id": "phase-change-mass", "name": "Phase-change thermal mass", "kind": "studio", "summary": "Enthalpy storage with a finite linear melting interval; constant sensible heat capacity, no supercooling or hysteresis", "behavior": "Conserving component solved simultaneously with the connected network. 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Checks below were verified in the native execution engine.", "url": "https://design.lemonergy.com/cosim.html?example=physical-phase-change-mass", "label": "Open Studio example", "inputs": [ { "port": "massKg", "label": "Mass", "value": 1, "unit": "kg" }, { "port": "specificHeatJkgK", "label": "Specific heat capacity", "value": 2, "unit": "J/(kg K)" }, { "port": "latentHeatJkg", "label": "Latent heat", "value": 100, "unit": "J/kg" }, { "port": "solidusK", "label": "Solidus temperature", "value": 310, "unit": "K" } ], "checks": [ { "port": "mass/temperature", "label": "temperature", "atS": 1, "value": 311, "unit": "K", "tolerance": 0.00031100000000000273 }, { "port": "mass/liquidFraction", "label": "liquidFraction", "atS": 1, "value": 0.1, "unit": "fraction", "tolerance": 1.0000000000020123e-07 }, { "port": "mass/storedEnergy", "label": "storedEnergy", "atS": 1, "value": 12, "unit": "J", "tolerance": 1.2000000000020007e-05 } ] }, "limits": [ "Enthalpy storage with a finite linear melting interval; constant sensible heat capacity, no supercooling or hysteresis", "Demonstration parameters are not calibrated hardware data. 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Singular or incompatible ideal constraints and unsupported state ranges stop the run." ], "references": [ "openstax-heat", "physical-enthalpy" ], "availability": { "status": "released", "label": "Available in Lemonergy Studio", "detail": "The bundled example is available in the production release verified on 28 October 2026. The parameters and examples here are synthetic teaching fixtures, not a characterized cell or a validated operating limit." }, "evidence": [ "docs/glossary/native-block-verification.json" ], "sourceRepository": "Lemonergy Studio public contract", "sourceRevision": "verification-2026-10-27", "caseIds": [ "native-thermal-mass", "native-edge-cooling-plate", "native-parallel-cooling-plate", "native-u-cooling-plate" ], "connectionGuide": { "kind": "thermal-mass", "title": "A load is a body with stored heat", "summary": "In the plate example, load1 to load4 are passive thermal masses. Their temperatures change as heat crosses their h terminals.", "concepts": [ { "id": "thermal-mass", "label": "Thermal mass" }, { "id": "heat-transfer-modes", "label": "Heat transfer" }, { "id": "thermal-model", "label": "Thermal model" }, { "id": "specific-heat-capacity", "label": "Specific heat capacity" } ] }, "type": "thermal-mass", "implementationId": "thermal-mass", "url": "https://lemonergy.com/learn/glossary/blocks/thermal-mass/", "documentationUrl": "https://lemonergy.com/learn/glossary/blocks/thermal-mass/", "sourceFile": "block-library.json", "reviewed": "2026-10-27", "releaseEvidence": { "environment": "production", "status": "verified", "revision": "e76cadfc203e15eb41f3478d8b1044a5b851953d", "verifiedOn": "2026-10-28", "exampleUrls": [ "https://design.lemonergy.com/cosim.html?example=physical-thermal-mass" ] }, "studioHelp": { "type": "thermal-mass", "namespace": "physical", "slug": "thermal-mass", "canonicalSlug": "thermal-mass", "existing": true, "dynamic": false, "scene": { "kind": "component", "componentId": "reference", "type": "thermal-mass", "name": "Thermal mass", "domain": "thermal", "family": "thermal-storage", "operation": "Stores sensible heat; net heat input changes temperature according to mass times specific heat.", "mechanism": [ "Net heat flow", "Heat capacity", "Temperature" ], "ports": [ { "id": "h", "domain": "thermal", "kind": "conserving", "label": "Stored-heat body contact", "net": null, "peers": [] } ], "terms": [ { "type": "thermal-heat-source", "label": "Heat flow source" }, { "type": "thermal-conductor", "label": "Thermal conductor" } ], "symbol": [ { "tag": "rect", "attrs": { "x": 65, "y": 10, "width": 70, "height": 60, "rx": 3 } }, { "tag": "path", "attrs": { "d": "M10 40H65M80 20V60M100 20V60M120 20V60" } } ], "selection": {}, "commands": [], "outputs": [ { "id": "temperature", "quantity": "temperature", "declared": true, "consumers": [], "label": "temperature", "unit": "K" }, { "id": "storedEnergy", "quantity": "energy", "declared": true, "consumers": [], "label": "stored Energy", "unit": "J" } ], "parameters": [ { "id": "massKg", "default": 1, "unit": "kg", "min": 1e-09, "max": 1000000000, "value": 1 }, { "id": "specificHeatJkgK", "default": 1000, "unit": "J/(kg K)", "min": 1e-06, "max": 1000000000, "value": 1000 }, { "id": "initialTemperatureK", "default": 300, "unit": "K", "min": 0, "max": 5000, "value": 300 } ] } } } }, { "id": "topic:topic-thermal", "type": "Topic", "label": "Thermal management and heat transfer", "properties": { "id": "topic-thermal", "name": "Thermal management and heat transfer", "lede": "How heat is made, moved and removed in cells and packs, and the hardware that keeps a battery at the right temperature.", "context": "Select spatial detail for the question.", "example": "Equal total heat in different layouts can produce different gradients. Average temperature can miss a hot spot.", "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/", "lesson_label": "Open temperature and aging" } }, { "id": "term:thermal-mass", "type": "Term", "label": "Thermal mass", "properties": { "id": "thermal-mass", "name": "Thermal mass", "aka": [ "thermal inertia", "thermal time constant" ], "section": "topic-thermal", "definition": "A body’s total heat capacity seen as a buffer against temperature change. A 500 kg pack at about 1 kJ/(kg·K) stores roughly 500 kJ per kelvin, so 10 kW of uncooled heat warms it only about 1.2 K a minute. Together with the thermal resistance to the coolant it sets the pack’s thermal time constant.", "formula": "τ = m·cₚ·R_th", "related": [ "specific-heat-capacity", "thermal-resistance", "thermal-model", "phase-change-material", "thermal-management" ], "example": { "title": "Calculate a thermal time constant", "text": "With mass 0.5 kg, cₚ = 900 J/(kg·K) and R_th = 2 K/W, the lumped thermal time constant is 900 s, or 15 min. The calculation assumes a nearly uniform internal temperature." }, "url": "https://lemonergy.com/learn/glossary/thermal-mass/", "mentions": [] } }, { "id": "term:thermal-characterisation", "type": "Term", "label": "Thermal characterisation", "properties": { "id": "thermal-characterisation", "name": "Thermal characterisation", "aka": [ "heat capacity test", "entropy test" ], "section": "topic-testing", "definition": "Measuring the thermal properties a model needs: specific heat capacity in a calorimeter, thermal conductivity through and along the layers, the entropy coefficient from OCV against temperature, and heat generation under load. Without them a thermal model is a guess.", "related": [ "heat-generation", "entropy-coefficient", "thermal-model", "accelerating-rate-calorimetry" ], "url": "https://lemonergy.com/learn/glossary/thermal-characterisation/", "mentions": [ "open-circuit-voltage", "thermal-conductivity", "specific-heat-capacity" ] } }, { "id": "term:thermal-model", "type": "Term", "label": "Thermal model", "properties": { "id": "thermal-model", "name": "Thermal model", "aka": [ "lumped thermal model" ], "section": "topic-thermal", "definition": "A model of cell temperature: at its simplest one thermal mass with heat generation inside and convection outside, at its most detailed a 3D simulation of the pack. Temperature feeds back into every rate, so electrical and thermal models are usually solved together.", "related": [ "heat-generation", "thermal-management", "arrhenius", "newman-model", "thermal-characterisation" ], "url": "https://lemonergy.com/learn/glossary/thermal-model/", "mentions": [ "thermal-mass", "heat-transfer-modes" ] } }, { "id": "term:heat-generation", "type": "Term", "label": "Heat generation", "properties": { "id": "heat-generation", "name": "Heat generation", "aka": [ "Bernardi equation" ], "section": "topic-thermal", "definition": "The heat a cell produces in operation: an irreversible part equal to current times overpotential, and a reversible part from the entropy change, I·T·dE/dT. The Bernardi equation sums them and feeds every thermal model.", "formula": "q = I(V − E_OCV) + I·T·(dE/dT)", "unit": "W", "related": [ "entropy-coefficient", "internal-resistance", "thermal-model", "thermal-management", "exothermic" ], "example": { "title": "Keep reversible and irreversible heat separate", "text": "With charging current +5 A and terminal voltage 0.10 V above OCV, the irreversible term is 0.50 W. At 300 K with dE/dT = +0.1 mV/K, the reversible contribution is +0.15 W, giving 0.65 W under this sign convention." }, "url": "https://lemonergy.com/learn/glossary/heat-generation/", "mentions": [ "overpotential" ] } }, { "id": "term:thermal-diffusivity", "type": "Term", "label": "Thermal diffusivity", "properties": { "id": "thermal-diffusivity", "name": "Thermal diffusivity", "abbr": "α", "section": "topic-thermal", "definition": "How quickly temperature evens out inside a material: thermal conductivity divided by density times specific heat. Heat spreads a distance L in roughly L²/α, so crossing a 10 mm cell at about 0.2 mm²/s through-plane takes several minutes, while aluminium, near 100 mm²/s, equalises almost at once.", "formula": "α = k / (ρ·cₚ)", "unit": "m²/s", "related": [ "thermal-conductivity", "specific-heat-capacity", "thermal-gradient", "biot-number", "thermal-model" ], "example": { "title": "Compare heat-spreading rates", "text": "For an illustrative material with k = 1 W/(m·K), density 2000 kg/m³ and cₚ = 1000 J/(kg·K), α = 5×10⁻⁷ m²/s. A higher α means a temperature disturbance spreads faster for the same geometry." }, "url": "https://lemonergy.com/learn/glossary/thermal-diffusivity/", "mentions": [] } }, { "id": "term:pouch-cell", "type": "Term", "label": "Pouch cell", "properties": { "id": "pouch-cell", "name": "Pouch cell", "aka": [ "lithium polymer cell", "LiPo" ], "section": "topic-chemistries", "definition": "A cell sealed in a flexible bag of aluminium laminated with plastic, holding stacked electrode sheets in larger cells or a flattened wound roll in many small ones. It is light and easy to cool, but needs outside support and can visibly swell if gas forms inside.", "related": [ "pouch-foil", "stacking", "swelling", "degassing", "prismatic-cell" ], "lesson": "fundamentals/cell-production/#formats", "example": { "title": "Include mechanical support", "text": "A pouch encloses layered electrodes. Support provided by the module is part of the complete design, separate from the active layers." }, "url": "https://lemonergy.com/learn/glossary/pouch-cell/", "mentions": [ "electrode" ] } }, { "id": "visual:thermal", "type": "Visual", "label": "Heat approaches an equilibrium", "properties": { "title": "Heat approaches an equilibrium", "summary": "Thermal resistance sets the steady temperature rise; thermal mass sets the response time.", "readout": "Steady rise: 10 K. Time constant: 8.333 min.", "formula": "ΔT = P R_th [1 − exp(−t / (C_th R_th))]", "note": "C_th = 500 J/K, fixed ambient and heat input, uniform temperature.", "software": { "status": "reference", "label": "Reference concept", "body": "Analysis → Charge session supports optional lumped thermal behavior. This independent explanation uses a 500 J/K thermal mass and constant heat input; it is not an application simulation result.", "href": "https://design.lemonergy.com/" }, "html": "
Temperature above ambient
Temperature above ambientTime (min) versus Temperature rise (K). Lumped response. Interpretation follows the graphs.001515303045456060Time (min)Temperature rise (K)
Lumped response
" } } ] }